1 a catalyst (for sth) a person or a thing that causes change 引起变化的人或事物: The scandal was the catalyst for the President's election defeat. 这丑闻是促使总统落选的重要因素。

2 a substance that makes a chemical reaction happen faster 催化剂 catalytic /ˌkætəˈlɪtɪk ||; ˌkætḷˈɪtɪk/ adj